IMHO, Mine had the right idea(or at least the right level of anger),

spoiler

over some not-so-rare books, while Dennis is almost-as criminal as the arsonists in his desire to just run away when a good chunk of Atelier’s books that went up in flames were One-of-A-Kind.

In his place, I would go to war with the kingdom itself, or at least eliminate Night Mist’s leadership and duel Vigor(to the death), as well as Joseph Workstadt. Hell, he should have dueled Joseph over the business with Atelier’s inherittance, but … am I wrong?